[syzbot] [netfilter?] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work (2)

[syzbot] [netfilter?] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    03d38806a902 Merge tag 'thermal-6.14-rc5' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=115128b7980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8f2f8fb6ad08b539
dashboard link: https://syzkaller.appspot.com/bug?extid=5d8c5789c8cb076b2c25
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155128b7980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-03d38806.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1d06fe5cd112/vmlinux-03d38806.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1615b4c586c7/bzImage-03d38806.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5d8c5789c8cb076b2c25@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in nft_ctx_update include/net/netfilter/nf_tables.h:1861 [inline]
BUG: KASAN: slab-use-after-free in nft_commit_release net/netfilter/nf_tables_api.c:9958 [inline]
BUG: KASAN: slab-use-after-free in nf_tables_trans_destroy_work+0x9af/0xae0 net/netfilter/nf_tables_api.c:10023
Read of size 2 at addr ffff88804ee0e9c4 by task kworker/0:3/6521

CPU: 0 UID: 0 PID: 6521 Comm: kworker/0:3 Not tainted 6.14.0-rc4-syzkaller-00248-g03d38806a902 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events nf_tables_trans_destroy_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xd9/0x110 mm/kasan/report.c:634
 nft_ctx_update include/net/netfilter/nf_tables.h:1861 [inline]
 nft_commit_release net/netfilter/nf_tables_api.c:9958 [inline]
 nf_tables_trans_destroy_work+0x9af/0xae0 net/netfilter/nf_tables_api.c:10023
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3400
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 14088:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 nf_tables_newtable+0xd79/0x1b40 net/netfilter/nf_tables_api.c:1574
 nfnetlink_rcv_batch+0x1a2a/0x24e0 net/netfilter/nfnetlink.c:524
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:647 [inline]
 nfnetlink_rcv+0x3c3/0x430 net/netfilter/nfnetlink.c:665
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1882
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:733 [inline]
 ____sys_sendmsg+0xaaf/0xc90 net/socket.c:2573
 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2627
 __sys_sendmsg+0x16e/0x220 net/socket.c:2659
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 14086:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2353 [inline]
 slab_free mm/slub.c:4609 [inline]
 kfree+0x2c4/0x4d0 mm/slub.c:4757
 nf_tables_table_destroy+0xb3/0xf0 net/netfilter/nf_tables_api.c:1781
 __nft_release_table+0xf8b/0x13d0 net/netfilter/nf_tables_api.c:11818
 nft_rcv_nl_event+0x4c9/0x6b0 net/netfilter/nf_tables_api.c:11876
 notifier_call_chain+0xb7/0x410 kernel/notifier.c:85
 blocking_notifier_call_chain kernel/notifier.c:380 [inline]
 blocking_notifier_call_chain+0x69/0xa0 kernel/notifier.c:368
 netlink_release+0x1838/0x1fe0 net/netlink/af_netlink.c:764
 __sock_release+0xb0/0x270 net/socket.c:647
 sock_close+0x1c/0x30 net/socket.c:1398
 __fput+0x3ff/0xb70 fs/file_table.c:464
 task_work_run+0x14e/0x250 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_record_aux_stack+0xb8/0xd0 mm/kasan/generic.c:548
 insert_work+0x36/0x230 kernel/workqueue.c:2183
 __queue_work+0x97e/0x10f0 kernel/workqueue.c:2341
 queue_work_on+0x11a/0x140 kernel/workqueue.c:2392
 queue_work include/linux/workqueue.h:662 [inline]
 schedule_work include/linux/workqueue.h:723 [inline]
 __rhashtable_remove_fast_one include/linux/rhashtable.h:1069 [inline]
 __rhashtable_remove_fast.constprop.0.isra.0+0xed7/0x12b0 include/linux/rhashtable.h:1093
 rhltable_remove include/linux/rhashtable.h:1144 [inline]
 nft_chain_del+0x57/0x1a0 net/netfilter/nf_tables_api.c:10207
 __nft_release_table+0xf0e/0x13d0 net/netfilter/nf_tables_api.c:11814
 nft_rcv_nl_event+0x4c9/0x6b0 net/netfilter/nf_tables_api.c:11876
 notifier_call_chain+0xb7/0x410 kernel/notifier.c:85
 blocking_notifier_call_chain kernel/notifier.c:380 [inline]
 blocking_notifier_call_chain+0x69/0xa0 kernel/notifier.c:368
 netlink_release+0x1838/0x1fe0 net/netlink/af_netlink.c:764
 __sock_release+0xb0/0x270 net/socket.c:647
 sock_close+0x1c/0x30 net/socket.c:1398
 __fput+0x3ff/0xb70 fs/file_table.c:464
 task_work_run+0x14e/0x250 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88804ee0e800
 which belongs to the cache kmalloc-cg-512 of size 512
The buggy address is located 452 bytes inside of
 freed 512-byte region [ffff88804ee0e800, ffff88804ee0ea00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4ee0c
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff8880280fae01
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b04de00 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000000f5000000 ffff8880280fae01
head: 00fff00000000040 ffff88801b04de00 dead000000000122 0000000000000000
head: 0000000000000000 0000000080100010 00000000f5000000 ffff8880280fae01
head: 00fff00000000002 ffffea00013b8301 ffffffffffffffff 0000000000000000
head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5653, tgid 5653 (dhcpcd), ts 208176970817, free_ts 208162705163
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0xfce/0x2f80 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x221/0x2470 mm/page_alloc.c:4739
 alloc_pages_mpol+0x1fc/0x540 mm/mempolicy.c:2270
 alloc_slab_page mm/slub.c:2423 [inline]
 allocate_slab mm/slub.c:2587 [inline]
 new_slab+0x23d/0x330 mm/slub.c:2640
 ___slab_alloc+0xc5d/0x1720 mm/slub.c:3826
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3916
 __slab_alloc_node mm/slub.c:3991 [inline]
 slab_alloc_node mm/slub.c:4152 [inline]
 __do_kmalloc_node mm/slub.c:4293 [inline]
 __kmalloc_node_track_caller_noprof+0x2f1/0x510 mm/slub.c:4313
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:537
 __alloc_skb+0x164/0x380 net/core/skbuff.c:606
 alloc_skb include/linux/skbuff.h:1331 [inline]
 alloc_skb_with_frags+0xe4/0x850 net/core/skbuff.c:6522
 sock_alloc_send_pskb+0x7f1/0x980 net/core/sock.c:2914
 unix_dgram_sendmsg+0x45e/0x1880 net/unix/af_unix.c:2017
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:733 [inline]
 sock_write_iter+0x4fe/0x5b0 net/socket.c:1137
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0x5ae/0x1150 fs/read_write.c:679
 ksys_write+0x207/0x250 fs/read_write.c:731
page last free pid 14050 tgid 14050 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_frozen_pages+0x6db/0xfb0 mm/page_alloc.c:2660
 __put_partials+0x14c/0x170 mm/slub.c:3153
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4e/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4115 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 kmem_cache_alloc_noprof+0x226/0x3d0 mm/slub.c:4171
 ptlock_alloc+0x1f/0x70 mm/memory.c:7055
 ptlock_init include/linux/mm.h:2972 [inline]
 pagetable_pte_ctor include/linux/mm.h:3020 [inline]
 __pte_alloc_one_noprof include/asm-generic/pgalloc.h:73 [inline]
 pte_alloc_one+0x74/0x390 arch/x86/mm/pgtable.c:44
 do_fault_around mm/memory.c:5355 [inline]
 do_read_fault mm/memory.c:5394 [inline]
 do_fault mm/memory.c:5537 [inline]
 do_pte_missing+0x1aff/0x3e10 mm/memory.c:4058
 handle_pte_fault mm/memory.c:5900 [inline]
 __handle_mm_fault+0x1166/0x2c60 mm/memory.c:6043
 handle_mm_fault+0x3fa/0xaa0 mm/memory.c:6212
 do_user_addr_fault+0x60d/0x13f0 arch/x86/mm/fault.c:1337
 handle_page_fault arch/x86/mm/fault.c:1480 [inline]
 exc_page_fault+0x5c/0xc0 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

Memory state around the buggy address:
 ffff88804ee0e880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88804ee0e900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88804ee0e980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88804ee0ea00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88804ee0ea80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [netfilter?] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work (2)

[Hillf Danton]

On Sun, 02 Mar 2025 03:57:27 -0800
> syzbot found the following issue on:
> 
> HEAD commit:    03d38806a902 Merge tag 'thermal-6.14-rc5' of git://git.ker..
> git tree:       upstream
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155128b7980000

#syz test

--- x/net/netfilter/nf_tables_api.c
+++ y/net/netfilter/nf_tables_api.c
@@ -10654,6 +10654,10 @@ static int nf_tables_commit(struct net *
 		mutex_unlock(&nft_net->commit_mutex);
 		return 0;
 	}
+	if (nft_net->flushed) {
+		mutex_unlock(&nft_net->commit_mutex);
+		return -EAGAIN;
+	}
 
 	nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
 
@@ -11251,6 +11255,7 @@ static int nf_tables_abort(struct net *n
 	else
 		nf_tables_module_autoload_cleanup(net);
 
+	nft_net->flushed = 0;
 	mutex_unlock(&nft_net->commit_mutex);
 
 	return ret;
@@ -11854,6 +11859,7 @@ static int nft_rcv_nl_event(struct notif
 	gc_seq = nft_gc_seq_begin(nft_net);
 
 	nf_tables_trans_destroy_flush_work();
+	nft_net->flushed = 1;
 again:
 	list_for_each_entry(table, &nft_net->tables, list) {
 		if (nft_table_has_owner(table) &&
@@ -11903,6 +11909,7 @@ static int __net_init nf_tables_init_net
 	nft_net->base_seq = 1;
 	nft_net->gc_seq = 0;
 	nft_net->validate_state = NFT_VALIDATE_SKIP;
+	nft_net->flushed = 0;
 
 	return 0;
 }
--- x/include/net/netfilter/nf_tables.h
+++ y/include/net/netfilter/nf_tables.h
@@ -1915,6 +1915,7 @@ struct nftables_pernet {
 	unsigned int		base_seq;
 	unsigned int		gc_seq;
 	u8			validate_state;
+	u8			flushed;
 };
 
 extern unsigned int nf_tables_net_id;
--

Re: [syzbot] [netfilter?] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work (2)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING: bad unlock balance in nf_tables_abort

=====================================
WARNING: bad unlock balance detected!
6.14.0-rc5-syzkaller-g7eb172143d55-dirty #0 Not tainted
-------------------------------------
syz.0.20/6539 is trying to release lock (&nft_net->commit_mutex) at:
[<ffffffff898b345d>] nf_tables_module_autoload net/netfilter/nf_tables_api.c:10962 [inline]
[<ffffffff898b345d>] nf_tables_abort+0x29fd/0x3d60 net/netfilter/nf_tables_api.c:11254
but there are no more locks to release!

other info that might help us debug this:
no locks held by syz.0.20/6539.

stack backtrace:
CPU: 3 UID: 0 PID: 6539 Comm: syz.0.20 Not tainted 6.14.0-rc5-syzkaller-g7eb172143d55-dirty #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_unlock_imbalance_bug kernel/locking/lockdep.c:5289 [inline]
 print_unlock_imbalance_bug+0x1aa/0x1f0 kernel/locking/lockdep.c:5263
 __lock_release kernel/locking/lockdep.c:5528 [inline]
 lock_release+0x525/0x6f0 kernel/locking/lockdep.c:5872
 __mutex_unlock_slowpath+0xa3/0x6a0 kernel/locking/mutex.c:891
 nf_tables_module_autoload net/netfilter/nf_tables_api.c:10962 [inline]
 nf_tables_abort+0x29fd/0x3d60 net/netfilter/nf_tables_api.c:11254
 nfnetlink_rcv_batch+0xabb/0x24e0 net/netfilter/nfnetlink.c:568
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:647 [inline]
 nfnetlink_rcv+0x3c3/0x430 net/netfilter/nfnetlink.c:665
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1882
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:733 [inline]
 ____sys_sendmsg+0xaaf/0xc90 net/socket.c:2573
 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2627
 __sys_sendmsg+0x16e/0x220 net/socket.c:2659
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8dd078d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8dd1634038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8dd09a5fa0 RCX: 00007f8dd078d169
RDX: 0000000000000000 RSI: 000040000000c2c0 RDI: 0000000000000003
RBP: 00007f8dd080e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8dd09a5fa0 R15: 00007fff3449f258
 </TASK>


Tested on:

commit:         7eb17214 Linux 6.14-rc5
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1382a464580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=da4b04ae798b7ef6
dashboard link: https://syzkaller.appspot.com/bug?extid=5d8c5789c8cb076b2c25
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=125ca464580000

Re: [syzbot] [netfilter?] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work (2)

[Hillf Danton]

On Sun, 02 Mar 2025 03:57:27 -0800
> syzbot found the following issue on:
> 
> HEAD commit:    03d38806a902 Merge tag 'thermal-6.14-rc5' of git://git.ker..
> git tree:       upstream
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=155128b7980000

#syz test

--- x/include/net/netfilter/nf_tables.h
+++ y/include/net/netfilter/nf_tables.h
@@ -1915,6 +1915,7 @@ struct nftables_pernet {
 	unsigned int		base_seq;
 	unsigned int		gc_seq;
 	u8			validate_state;
+	u8			flushed;
 };
 
 extern unsigned int nf_tables_net_id;
--- x/net/netfilter/nf_tables_api.c
+++ y/net/netfilter/nf_tables_api.c
@@ -10654,6 +10654,9 @@ static int nf_tables_commit(struct net *
 		mutex_unlock(&nft_net->commit_mutex);
 		return 0;
 	}
+	if (nft_net->flushed) {
+		return -EAGAIN;
+	}
 
 	nft_ctx_init(&ctx, net, skb, nlh, NFPROTO_UNSPEC, NULL, NULL, NULL);
 
@@ -11251,6 +11254,7 @@ static int nf_tables_abort(struct net *n
 	else
 		nf_tables_module_autoload_cleanup(net);
 
+	nft_net->flushed = 0;
 	mutex_unlock(&nft_net->commit_mutex);
 
 	return ret;
@@ -11854,6 +11858,7 @@ static int nft_rcv_nl_event(struct notif
 	gc_seq = nft_gc_seq_begin(nft_net);
 
 	nf_tables_trans_destroy_flush_work();
+	nft_net->flushed = 1;
 again:
 	list_for_each_entry(table, &nft_net->tables, list) {
 		if (nft_table_has_owner(table) &&
@@ -11903,6 +11908,7 @@ static int __net_init nf_tables_init_net
 	nft_net->base_seq = 1;
 	nft_net->gc_seq = 0;
 	nft_net->validate_state = NFT_VALIDATE_SKIP;
+	nft_net->flushed = 0;
 
 	return 0;
 }
--

Re: [syzbot] [netfilter?] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work (2)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+5d8c5789c8cb076b2c25@syzkaller.appspotmail.com
Tested-by: syzbot+5d8c5789c8cb076b2c25@syzkaller.appspotmail.com

Tested on:

commit:         7eb17214 Linux 6.14-rc5
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123f27a0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=da4b04ae798b7ef6
dashboard link: https://syzkaller.appspot.com/bug?extid=5d8c5789c8cb076b2c25
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=160f27a0580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work
Author: fw@strlen.de

#syz test

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 60d5dcdb289c..c428a152d907 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1891,7 +1891,7 @@ void nft_chain_filter_fini(void);
 void __init nft_chain_route_init(void);
 void nft_chain_route_fini(void);
 
-void nf_tables_trans_destroy_flush_work(void);
+void nf_tables_trans_destroy_flush_work(struct net *net);
 
 int nf_msecs_to_jiffies64(const struct nlattr *nla, u64 *result);
 __be64 nf_jiffies64_to_msecs(u64 input);
@@ -1905,6 +1905,8 @@ static inline int nft_request_module(struct net *net, const char *fmt, ...) { re
 struct nftables_pernet {
 	struct list_head	tables;
 	struct list_head	commit_list;
+	struct list_head	destroy_list;
+	struct list_head	gc_list;
 	struct list_head	commit_set_list;
 	struct list_head	binding_list;
 	struct list_head	module_list;
@@ -1915,6 +1917,7 @@ struct nftables_pernet {
 	unsigned int		base_seq;
 	unsigned int		gc_seq;
 	u8			validate_state;
+	struct work_struct	destroy_work;
 };
 
 extern unsigned int nf_tables_net_id;
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a34de9c17cf1..e9c46fd77498 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -34,10 +34,7 @@ unsigned int nf_tables_net_id __read_mostly;
 static LIST_HEAD(nf_tables_expressions);
 static LIST_HEAD(nf_tables_objects);
 static LIST_HEAD(nf_tables_flowtables);
-static LIST_HEAD(nf_tables_destroy_list);
-static LIST_HEAD(nf_tables_gc_list);
 static DEFINE_SPINLOCK(nf_tables_destroy_list_lock);
-static DEFINE_SPINLOCK(nf_tables_gc_list_lock);
 
 enum {
 	NFT_VALIDATE_SKIP	= 0,
@@ -109,6 +106,8 @@ static const u8 nft2audit_op[NFT_MSG_MAX] = { // enum nf_tables_msg_types
 	[NFT_MSG_GETSETELEM_RESET] = AUDIT_NFT_OP_SETELEM_RESET,
 };
 
+static void nf_tables_trans_gc_work(struct list_head *gc_list);
+
 static void nft_validate_state_update(struct nft_table *table, u8 new_validate_state)
 {
 	switch (table->validate_state) {
@@ -125,10 +124,6 @@ static void nft_validate_state_update(struct nft_table *table, u8 new_validate_s
 	table->validate_state = new_validate_state;
 }
 static void nf_tables_trans_destroy_work(struct work_struct *w);
-static DECLARE_WORK(trans_destroy_work, nf_tables_trans_destroy_work);
-
-static void nft_trans_gc_work(struct work_struct *work);
-static DECLARE_WORK(trans_gc_work, nft_trans_gc_work);
 
 static void nft_ctx_init(struct nft_ctx *ctx,
 			 struct net *net,
@@ -10006,13 +10001,18 @@ static void nft_commit_release(struct nft_trans *trans)
 
 static void nf_tables_trans_destroy_work(struct work_struct *w)
 {
+	struct nftables_pernet *nft_net = container_of(w, struct nftables_pernet, destroy_work);
 	struct nft_trans *trans, *next;
+	LIST_HEAD(gc_head);
 	LIST_HEAD(head);
 
 	spin_lock(&nf_tables_destroy_list_lock);
-	list_splice_init(&nf_tables_destroy_list, &head);
+	list_splice_init(&nft_net->gc_list, &gc_head);
+	list_splice_init(&nft_net->destroy_list, &head);
 	spin_unlock(&nf_tables_destroy_list_lock);
 
+	nf_tables_trans_gc_work(&gc_head);
+
 	if (list_empty(&head))
 		return;
 
@@ -10024,9 +10024,11 @@ static void nf_tables_trans_destroy_work(struct work_struct *w)
 	}
 }
 
-void nf_tables_trans_destroy_flush_work(void)
+void nf_tables_trans_destroy_flush_work(struct net *net)
 {
-	flush_work(&trans_destroy_work);
+	struct nftables_pernet *nft_net = nft_pernet(net);
+
+	flush_work(&nft_net->destroy_work);
 }
 EXPORT_SYMBOL_GPL(nf_tables_trans_destroy_flush_work);
 
@@ -10277,16 +10279,11 @@ static bool nft_trans_gc_work_done(struct nft_trans_gc *trans)
 	return true;
 }
 
-static void nft_trans_gc_work(struct work_struct *work)
+static void nf_tables_trans_gc_work(struct list_head *gc_list)
 {
 	struct nft_trans_gc *trans, *next;
-	LIST_HEAD(trans_gc_list);
-
-	spin_lock(&nf_tables_gc_list_lock);
-	list_splice_init(&nf_tables_gc_list, &trans_gc_list);
-	spin_unlock(&nf_tables_gc_list_lock);
 
-	list_for_each_entry_safe(trans, next, &trans_gc_list, list) {
+	list_for_each_entry_safe(trans, next, gc_list, list) {
 		list_del(&trans->list);
 		if (!nft_trans_gc_work_done(trans)) {
 			nft_trans_gc_destroy(trans);
@@ -10326,11 +10323,13 @@ void nft_trans_gc_elem_add(struct nft_trans_gc *trans, void *priv)
 
 static void nft_trans_gc_queue_work(struct nft_trans_gc *trans)
 {
-	spin_lock(&nf_tables_gc_list_lock);
-	list_add_tail(&trans->list, &nf_tables_gc_list);
-	spin_unlock(&nf_tables_gc_list_lock);
+	struct nftables_pernet *nft_net = nft_pernet(trans->net);
+
+	spin_lock(&nf_tables_destroy_list_lock);
+	list_add_tail(&trans->list, &nft_net->gc_list);
+	spin_unlock(&nf_tables_destroy_list_lock);
 
-	schedule_work(&trans_gc_work);
+	schedule_work(&nft_net->destroy_work);
 }
 
 static int nft_trans_gc_space(struct nft_trans_gc *trans)
@@ -10484,11 +10483,11 @@ static void nf_tables_commit_release(struct net *net)
 
 	trans->put_net = true;
 	spin_lock(&nf_tables_destroy_list_lock);
-	list_splice_tail_init(&nft_net->commit_list, &nf_tables_destroy_list);
+	list_splice_tail_init(&nft_net->commit_list, &nft_net->destroy_list);
 	spin_unlock(&nf_tables_destroy_list_lock);
 
 	nf_tables_module_autoload_cleanup(net);
-	schedule_work(&trans_destroy_work);
+	schedule_work(&nft_net->destroy_work);
 
 	mutex_unlock(&nft_net->commit_mutex);
 }
@@ -11853,7 +11852,7 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event,
 
 	gc_seq = nft_gc_seq_begin(nft_net);
 
-	nf_tables_trans_destroy_flush_work();
+	nf_tables_trans_destroy_flush_work(net);
 again:
 	list_for_each_entry(table, &nft_net->tables, list) {
 		if (nft_table_has_owner(table) &&
@@ -11895,6 +11894,8 @@ static int __net_init nf_tables_init_net(struct net *net)
 
 	INIT_LIST_HEAD(&nft_net->tables);
 	INIT_LIST_HEAD(&nft_net->commit_list);
+	INIT_LIST_HEAD(&nft_net->destroy_list);
+	INIT_LIST_HEAD(&nft_net->gc_list);
 	INIT_LIST_HEAD(&nft_net->commit_set_list);
 	INIT_LIST_HEAD(&nft_net->binding_list);
 	INIT_LIST_HEAD(&nft_net->module_list);
@@ -11903,6 +11904,7 @@ static int __net_init nf_tables_init_net(struct net *net)
 	nft_net->base_seq = 1;
 	nft_net->gc_seq = 0;
 	nft_net->validate_state = NFT_VALIDATE_SKIP;
+	INIT_WORK(&nft_net->destroy_work, nf_tables_trans_destroy_work);
 
 	return 0;
 }
@@ -11936,21 +11938,20 @@ static void __net_exit nf_tables_exit_net(struct net *net)
 	nft_gc_seq_end(nft_net, gc_seq);
 
 	mutex_unlock(&nft_net->commit_mutex);
+
+	cancel_work_sync(&nft_net->destroy_work);
+
 	WARN_ON_ONCE(!list_empty(&nft_net->tables));
 	WARN_ON_ONCE(!list_empty(&nft_net->module_list));
 	WARN_ON_ONCE(!list_empty(&nft_net->notify_list));
-}
-
-static void nf_tables_exit_batch(struct list_head *net_exit_list)
-{
-	flush_work(&trans_gc_work);
+	WARN_ON_ONCE(!list_empty(&nft_net->destroy_list));
+	WARN_ON_ONCE(!list_empty(&nft_net->gc_list));
 }
 
 static struct pernet_operations nf_tables_net_ops = {
 	.init		= nf_tables_init_net,
 	.pre_exit	= nf_tables_pre_exit_net,
 	.exit		= nf_tables_exit_net,
-	.exit_batch	= nf_tables_exit_batch,
 	.id		= &nf_tables_net_id,
 	.size		= sizeof(struct nftables_pernet),
 };
@@ -12029,10 +12030,7 @@ static void __exit nf_tables_module_exit(void)
 	unregister_netdevice_notifier(&nf_tables_flowtable_notifier);
 	nft_chain_filter_fini();
 	nft_chain_route_fini();
-	nf_tables_trans_destroy_flush_work();
 	unregister_pernet_subsys(&nf_tables_net_ops);
-	cancel_work_sync(&trans_gc_work);
-	cancel_work_sync(&trans_destroy_work);
 	rcu_barrier();
 	rhltable_destroy(&nft_objname_ht);
 	nf_tables_core_module_exit();
diff --git a/net/netfilter/nft_compat.c b/net/netfilter/nft_compat.c
index 7ca4f0d21fe2..72711d62fddf 100644
--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -228,7 +228,7 @@ static int nft_parse_compat(const struct nlattr *attr, u16 *proto, bool *inv)
 	return 0;
 }
 
-static void nft_compat_wait_for_destructors(void)
+static void nft_compat_wait_for_destructors(struct net *net)
 {
 	/* xtables matches or targets can have side effects, e.g.
 	 * creation/destruction of /proc files.
@@ -236,7 +236,7 @@ static void nft_compat_wait_for_destructors(void)
 	 * work queue.  If we have pending invocations we thus
 	 * need to wait for those to finish.
 	 */
-	nf_tables_trans_destroy_flush_work();
+	nf_tables_trans_destroy_flush_work(net);
 }
 
 static int
@@ -262,7 +262,7 @@ nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 
 	nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
 
-	nft_compat_wait_for_destructors();
+	nft_compat_wait_for_destructors(ctx->net);
 
 	ret = xt_check_target(&par, size, proto, inv);
 	if (ret < 0) {
@@ -515,7 +515,7 @@ __nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 
 	nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
 
-	nft_compat_wait_for_destructors();
+	nft_compat_wait_for_destructors(ctx->net);
 
 	return xt_check_match(&par, size, proto, inv);
 }

Re: [syzbot] [netfilter?] KASAN: slab-use-after-free Read in nf_tables_trans_destroy_work (2)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+5d8c5789c8cb076b2c25@syzkaller.appspotmail.com
Tested-by: syzbot+5d8c5789c8cb076b2c25@syzkaller.appspotmail.com

Tested on:

commit:         99fa936e Merge tag 'affs-6.14-rc5-tag' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10386fb8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=da4b04ae798b7ef6
dashboard link: https://syzkaller.appspot.com/bug?extid=5d8c5789c8cb076b2c25
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=177398b7980000

Note: testing is done by a robot and is best-effort only.